Cameras capture light properties from a light source. For example, digital cameras capture or measure the color distribution of a light source. The accuracy of such cameras, however, can be improved by comparing or otherwise calibrating a camera's measured light with a spectrometer's measured light from the same light source. A spectrometer is an instrument used to measure properties of light over a specific portion of the electromagnetic spectrum. FIGS. 1A and 1B are schematic partial illustrations of a conventional system 100 for collecting light within a camera. Referring to FIGS. 1A and 1B together, the light passes through a lens assembly or imaging lens 102, and the system 100 sends the light to an optical or spectrometer fiber optic input 104. The optical fiber 104 in turn transmits the light to a spectrometer (not shown). In the system 100 of FIGS. 1A and 1B, a mirror 106 is mounted to a pivoting arm 108 to selectively intercept a light path. In FIG. 1A, for example, the mirror 106 is positioned so that it reflects light into the optical fiber 104. In this position however, light is blocked from reaching an image sensor 110 (e.g., CCD). By pivoting the arm out of the light path 112 as shown in FIG. 1B, the light path 112 is now unobstructed and the CCD 110 can collect the full image. As shown in FIGS. 1A and 1B, the input end of the optical fiber 104 is near the focal plane of the imaging lens 102. This means that the sample area is only as large as the input aperture of the optical fiber 104. Depending on the type of fiber used, this arrangement may sample only a small area of the image that the CCD 110 can capture.
In some applications, the mirror 106 can be replaced with a beamsplitter (not shown) configured to allow spectrometer samples to be collected at the same time as the CCD 110 collects the image. A beamsplitter can therefore eliminate the need to move the mirror 106 when the CCD 110 is used, however this can also result in a reduction of the total light that reaches the optical input 104 and the CCD 110. A beamsplitter may still be an advantage over the arrangement shown in FIGS. 1A and 1B, however, if the application needs to record spectrometer data at the same time as the CCD image is captured.
FIG. 2 is a schematic partial illustration of another conventional system 200 for collecting light from a full image field. More specifically, the system 200 of FIG. 2 illustrates an arrangement for sampling the full image field even if an input aperture 105 of the optical fiber 104 is smaller than the field of view. In this case, a field lens 202 is placed near an image plane 204 and gathers the light from the lens assembly or image lens 102 and mirror 206 to focus the light onto the input aperture 105 of the optical fiber 104. Similar to the system described above with reference to FIGS. 1A and 1B, the mirror 206 is mounted on a pivoting arm 208. A mask (not shown) can be positioned near the field lens 202 to specifically define the area that the spectrometer samples.